This invention relates to infrared light imaging scanners and, more particularly, to a novel reflector system useable therewith.
Cooled infrared detectors of high sensitivity, which are constituent components of imaging infrared scanners, employ a cold shield to reduce the total infrared radiation, other than the desired signal, reaching the detector(s). This cold shield often has a plate with an aperture through which the signal passes. This aperture constitutes a cold (aperture) stop. The outer surfaces of the cold shield are made reflective. In many infrared imaging systems, reflections of the interior of the cold stop by some elements of the optics ahead of the scan system cause a diffused, cool patch to appear in the center of the picture (i.e., the image). This is called the "Narcissus" effect, because the system is unable to stop looking at itself.
Attempts in the prior art to eliminate this effect have not been entirely successful and, additionally, suffer from inherent disadvantages well known to those of ordinary skill in the art. Such attempts have included: the introduction of an infrared light source into the preexisting optical path, with the source of such size and of such a signal level as to "cancel" the "Narcissus" effect; and, the employment of optical designs intended to diffuse use reflected signals as a trade-off of image sharpness.
My invention eliminates, or at the very least significantly reduces, the affect of the "Narcissus" effect without affecting image sharpness; and, thereby, constitutes a significant advance in the state-of-the-art.